Voice coil motor

ABSTRACT

The VCM according to an exemplary embodiment of the present disclosure includes a base unit, a mover including a bobbin arranged at an upper surface of the base unit and formed with a plurality of rotation prevention units along a periphery and a first driving unit arranged at a periphery of the bobbin, a stator including a yoke configured to the base unit to surround the mover and inner yoke units each extended to between the rotation prevention units, and a second driving unit oppositely arranged to the first driving unit, and an elastic member elastically supporting the mover, wherein an object occurrence preventing portion is formed between the rotation prevention unit and the inner yoke units to decrease a contact area between the rotation prevention unit and the inner yoke units.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 15/784,365 filed Oct. 16, 2017, which is aContinuation Application of U.S. patent application Ser. No. 14/419,780,filed on Feb. 5, 2015, which is a U.S National Stage Application under35 U.S.C. § 371 of PCT Application No. PCT/KR2013/005624, filed Jun. 26,2013, which claims priority to Korean Patent Application No.10-2012-0097323, filed Sep. 3, 2012.

TECHNICAL FIELD

The teachings in accordance with exemplary and non-limiting embodimentsof this disclosure relate generally to a VCM.

BACKGROUND ART

Recently, mobile communication devices such as mobile phones, gamemachines and tablet PCs are mounted with camera modules including imagesensors capable of storing an object in a digital still image or a videoimage.

A conventional camera module suffers from disadvantages in that that itis difficult to adjust a gap between an image sensor and a lens arrangedat a front surface of the image sensor, and it is also difficult toaccurately adjust a focus on an object, resulting in an image qualitydegradation of the digital image or video.

Concomitant with a recent development of a VCM (Voice Coil Motor), a gapbetween a lens and an image sensor can be adjusted to obtain anexcellent digital image or a video. In order to drive a VCM, the VCMincludes a stator including a magnet an a yoke, a rotor including a coilblock arranged inside the stator and arranged at a periphery of a bobbinmounted with a lens to generate an electromagnetic force in response toa driving current applied from an outside, and a cover arranged at thestator to cover the rotor.

The conventional VCM however suffers from disadvantages in that,although a portion of a bobbin is hitched at a yoke to prevent thebobbin from rotating abnormally, the bobbin contacted to the yoke allowsthe bobbin to generate particles such as fine dust or fine objects, andthe fine objects are in turn collected at an IR (Infrared) filterarranged at a bottom surface of the bobbin to deteriorate a displayquality of an image or a video.

DISCLOSURE Technical Problem

The present disclosure is to provide a VCM configured to decrease orinhibit generation of objects from a bobbin in a case a yoke and thebobbin are contacted, whereby a display quality degradation of an imageor a video can be prevented.

Technical problems to be solved by the present disclosure are notrestricted to the above-mentioned descriptions, and any other technicalproblems not mentioned so far will be clearly appreciated from thefollowing description by skilled in the art.

Technical Solution

In one exemplary embodiment of the present disclosure, there is provideda VCM, the VCM comprising:

a base unit, a mover including a bobbin arranged at an upper surface ofthe base unit and formed with a plurality of rotation prevention unitsalong a periphery and a first driving unit arranged at a periphery ofthe bobbin, a stator including a yoke configured to the base unit tosurround the mover and inner yoke units each extended to between therotation prevention units, and a second driving unit oppositely arrangedto the first driving unit, and an elastic member elastically supportingthe mover, wherein an object occurrence preventing portion is formedbetween the rotation prevention unit and the inner yoke units todecrease a contact area between the rotation prevention unit and theinner yoke units.

Advantageous Effects

A VCM according to an exemplary embodiment of the present disclosure hasan advantageous effect in that a contact area between a rotationprevention unit of a bobbin and an inner yoke unit of a yoke contactingthe rotation prevention unit of the bobbin is reduced to decrease orinhibit generation of objects generated from the rotation preventionunit when the rotation prevention unit of the bobbin and the inner yokeunit are brought into contact, whereby quality degradation of an imageor a video can be prevented.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a VCM according to anexemplary embodiment of the present disclosure.

FIG. 2 is an enlarged view of ‘A’ of FIG. 1.

FIG. 3 is a lateral view of a bobbin of FIG. 1.

FIG. 4 is a perspective view illustrating a bobbin according to anotherexemplary embodiment of the present disclosure.

BEST MODE

The disclosed exemplary embodiments and advantages thereof are bestunderstood by referring to the accompanying drawings. Like numbers referto like elements throughout. In the figures, certain layers, sizes,shapes, components or features may be exaggerated for clarity andconvenience.

Accordingly, the meaning of specific terms or words used in thespecification and claims should not be limited to the literal orcommonly employed sense, but should be construed or may be different inaccordance with the intention of a user or an operator and customaryusages. Therefore, the definition of the specific terms or words shouldbe based on the contents across the specification.

FIG. 1 is a cross-sectional view illustrating a VCM according to anexemplary embodiment of the present disclosure, FIG. 2 is an enlargedview of ‘A’ of FIG. 1, and FIG. 3 is a lateral view of a bobbin of FIG.1.

Referring to FIGS. 1, 2 and 3, a VCM (600) includes a base unit (100), amover (200), a stator (300), an elastic member (400) and an objectoccurrence preventing portion (500).

The base unit (100) takes a shape of a cubic plate, and is centrallyformed with a through hole (110) passing through an upper surface of thebase unit (100) and a bottom surface opposite to the upper surface. Eachof four corners formed on the upper surface of the base unit (100) iscoupled to a coupling pillar (120), where the coupling pillar (120) iscoupled to a spacer (330, described later). The mover (200) includes abobbin (210) and a first driving unit (220).

The bobbin (210) takes a shape of a cylinder opened at an upper surfaceand a bottom surface, and may be formed at an inner surface with afemale screw unit (212) for mounting at least one cylindrical lens. Thebobbin (210) is protrusively formed at a periphery (211) with aplurality of rotation prevention units (213) along the periphery (211)of the bobbin (210), where four rotation prevention units (213) may beformed along the periphery (211) of the bobbin (210), each spaced apartat a predetermined distance.

The rotation prevention units (213) prevent the rotation of the bobbin(210) by being hitched by an inner yoke portion (323) of a yoke (320,described later).

Although the exemplary embodiment of the present disclosure hasdescribed a plurality of rotation prevention units (213) protruded fromthe periphery (211) of the bobbin (210) each spaced apart at apredetermined distance, alternatively, it should be apparent that eachof the rotation prevention units (213) formed on the bobbin 210) maytake a recess shape concaved from the periphery (211) of the bobbin(210).

The first driving unit (220) is formed by winding a long wire insulatedby an insulating resin, and may be bonded to a surface of the rotationprevention unit (213) of the bobbin (210) using an adhesive. The stator(300) includes a second driving unit (310) and a yoke (320). Inaddition, the stator (300) may include a spacer (330).

In the exemplary embodiment of the present disclosure, the seconddriving unit (310) is arranged at an outside of the first driving unit(220). The second driving unit (310) is arranged opposite to the firstdriving unit (220). The second driving unit (310) includes four magnetsin a shape of a pillar, for example, and the four pillar-like magnetsare formed about the first driving unit (220), each spaced apart at apredetermined distance.

The yoke (320) is formed in a shape of a square plate, and includes ayoke upper plate (321) centrally formed with a round opening and yokelateral plates (322) extended from four edges of the yoke upper plate(321) to wrap the mover (100). Each of inner corners formed by a pair ofadjacent yoke lateral plates (322) is arranged with the second drivingunit (310). The yoke upper plate (321) is formed with an inner yoke unit(323) extended from the opening of the yoke upper plate (321) to therotation prevention units (213) of the bobbin (210).

The inner yoke unit (323) functions to prevent the bobbin (210) fromrotating by being contacted to the rotation prevention unit (213) in acase the bobbin (210) is rotated by leakage of electromagnetic fieldgenerated by the first driving unit (220) and turning effect generatedin a case a lens is mounted to the bobbin (210).

The elastic member (400) is arranged at a bottom surface of the bobbin(210) of the mover (200). In the exemplary embodiment of the presentinvention, the elastic member (400) may be formed in a pair, and each ofthe elastic members (400) is electrically insulated. The pair of elasticmembers (400) includes an inner elastic unit (410), an outer elasticunit (420) and a connection elastic unit (430).

The outer elastic unit (420), when seen in a top plan view, takes ashape of a bent strip, and is coupled to the coupling pillar (120) bybeing inserted into a pair of adjacent coupling pillars (120) of thebase unit (100). The inner elastic unit (410) is arranged at a bottomsurface of the bobbin (210). Thus, the inner elastic unit (410) takes ashape of a curved strip similar in shape to the bottom surface of thebobbin (210). The connection elastic unit (430), when seen in a top planview, is formed in a zigzag shape to be connected to the inner and outerelastic units (410, 420).

Referring to FIG. 1 again, an upper surface opposite to the bottomsurface of the bobbin (210) is arranged with an additional elasticmember (450) elastically supporting the bobbin (210). The spacer (330)serves to fix the elastic member (400), the additional elastic member(450), the mover (200) and the stator (300). The spacer (330) includesan upper spacer (332) and a bottom spacer (335), where the upper andbottom spacers (332, 335) are meshed. The bottom spacer (335) is coupledto the coupling pillars (120) of the base unit (100). The outer elasticunit (420) of the elastic member (400) is fixed between the bottomspacer (335) and an upper surface of the base unit (100), and theadditional elastic member (450) is fixed to a bottom surface of theupper spacer (332).

A cover (550) includes a cover upper plate (560) formed in a shape of asquare plate having a round opening for exposing a lens and a coverlateral plate (570) extended from an edge of the cover upper plate(560). The cover lateral plate (570) is coupled to the base unit (100).

Referring to FIGS. 2 and 3, the bobbin (210) is applied with a turningeffect in a case a lens is coupled to the bobbin (210), or the bobbin(210) vertically moves, and the bobbin (210) is horizontally rotated bythe turning effect applied to the bobbin (210). At this time, in a casethe bobbin (210) is rotated, the elastic member (400) and the additionalelastic member (450) are deformed or twisted to twist an optical axis ofthe mover (200) or to generate a driving defect of the mover (200).

As noted from the foregoing, the rotation of bobbin (210) is preventedby the rotation prevention unit (213) formed at the periphery of thebobbin (210) and the inner yoke unit (323) of the yoke (320), where, ina case the inner yoke unit (323) and the rotation prevention unit (213)are brought into contact, a fine objects may be generated from thebobbin (210) which is a molded material, and the fine objects may dropto be introduced to an upper surface of an IR (Infrared) filter arrangedat a rear surface of the base unit (100).

In a case the fine objects generated from the bobbin (210) areintroduced to an upper surface of an IR (Infrared) filter, there may begenerated a quality degradation of a digital image or a video due to thefine objects.

In the exemplary embodiment of the present disclosure, the VCM (600)includes the object occurrence preventing portions (500) preventinggeneration of objects by contact between the rotation prevention unit(213) of the bobbin (210) and the inner yoke unit (323) of the yoke(320). The object occurrence preventing portions (500) reduce orinhibit, for example, a generated amount of fine objects from therotation prevention unit (213) by reducing a contact area between therotation prevention unit (213) of the bobbin (210) and the inner yokeunit (3230 of the yoke (320). The object occurrence preventing portion(500) is formed at each lateral surface (213 a) of the rotationprevention unit (213) opposite to both lateral surfaces of the inneryoke unit (323) and contacting the inner yoke unit (323).

Particularly, the object occurrence preventing portion (500) formed onthe lateral surfaces (213 a) opposite to both lateral surfaces of theinner yoke unit (323) is formed in a shape of a staircase extendedoutwardly from the rotation prevention unit (213) for reducing thegenerated amount of fine objects from the rotation prevention unit(213).

To be more specific, in a case the both lateral surfaces of the inneryoke unit (323) are formed in a shape of a straight line, a first gap isformed between the lateral surfaces of the rotation prevention unit(213) and the lateral surfaces of the inner yoke unit (323), and asecond gap greater than the first gap is formed between the lateralsurfaces of the object occurrence preventing portion (500) and the inneryoke unit (323).

Hence, in a case the bobbin (210) is rotated, the lateral surfaces ofthe inner yoke unit (323) are brought into contact with each lateralsurface (213 a) of the area-reduced rotation prevention unit (213),whereby the generated amount of objects can be reduced or inhibited bythe rotation prevention unit (213). Furthermore, in view of the factthat the bobbin (210) is injection-molded, the object occurrencepreventing portion (500) may be formed at a predetermined depth from anupper surface of the bobbin (210).

Meanwhile, in a case the object occurrence preventing portion (500) isformed using an injection molding method, albeit being difficult, theobject occurrence preventing portion (500) may be intermittently formedwith at least two rotation prevention units (213) in order to reduce acontact area between the rotation prevention unit (213) of the bobbin(210) and the inner yoke unit (323).

Now, referring to FIG. 4, even if the amount of objects generated bycontact between the rotation prevention unit (213) and the inner yokeunit (323) in response to the rotation of bobbin (210) may be reduced orinhibited by the object occurrence preventing portion (500), a smallamount of objects can be generated, such that, in the exemplaryembodiment of the present disclosure, an object collecting member (590)may be formed at a floor surface of a groove formed by the rotationprevention unit (213) in order to prevent a small amount of objectsgenerated from the rotation prevention unit (213) from entering the IRfilter.

The object collecting member (590) may include a synthetic resin, forexample, having a sufficient viscosity for collecting the foreignobjects. The object collecting member (590) may include an epoxy resinhaving a viscosity.

Although the exemplary embodiment of the present disclosure hasdescribed and explained the reduction or inhibition of fine objects ofthe rotation prevention unit (213) of the bobbin (210) by forming arecess-shaped object occurrence preventing portion (500) on the rotationprevention unit (213) of the bobbin (210), alternatively, a portion ofthe inner yoke unit (323) of the yoke (320) opposite to the rotationprevention unit (213) may be cut to reduce a contact area with therotation prevention unit (213). Furthermore, in a case an objectoccurrence preventing portion is formed at a lateral surface of theinner yoke unit (323), a plurality of object occurrence preventingportions may be intermittently formed along the lateral surface of theinner yoke unit (323).

As apparent from the foregoing, a contact area between a rotationprevention unit of a bobbin and an inner yoke unit of a yoke contactingthe rotation prevention unit of the bobbin is reduced to decrease orinhibit generation of objects generated from the rotation preventionunit when the rotation prevention unit of the bobbin and the inner yokeunit are brought into contact, whereby quality degradation of an imageor a video can be prevented.

The previous description of the present disclosure is provided to enableany person skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to limit theexamples described herein, but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

The invention claimed is:
 1. A voice coil motor, comprising: a baseunit; a bobbin comprising a rotation prevention unit; a coil disposed onthe bobbin; a yoke comprising an upper plate, a lateral plate extendingfrom the upper plate and an inner unit extending from the upper plateand disposed in the lateral plate, a magnet disposed between the coiland the lateral plate of the yoke and facing the coil; and an elasticmember coupled to the bobbin, wherein the inner unit of the yoke isconfigured to be hitched by the rotation prevention unit to preventrotation of the bobbin, wherein a recess portion is formed in a shape ofa staircase having a first depth from an upper surface of the rotationprevention unit and a second depth formed from a lateral surface of therotation prevention unit, wherein a first gap is formed between thelateral surface of the rotation prevention unit and a lateral surface ofthe inner unit of the yoke facing the lateral surface of the rotationprevention unit, and a second gap is formed between a lateral surface ofthe recess portion and the lateral surface of the inner unit of the yokefacing the lateral surface of the recess portion, and wherein the secondgap is greater than the first gap.
 2. The voice coil motor of claim 1,wherein the lateral surface of the inner unit of the yoke contacts thelateral surface of the rotation prevention unit when the bobbin isrotated.
 3. The voice coil motor of claim 1, wherein the recess portionis configured to reduce a contact area between the rotation preventionunit and the inner unit of the yoke by the first depth of the recessportion, wherein the rotation prevention unit comprises a plurality ofrotation prevention units, and wherein the inner unit of the yokecomprises a plurality of inner units.
 4. The voice coil motor of claim1, wherein the elastic member comprises an upper elastic member disposedon an upper surface of the bobbin and not overlapped with the recessportion in an optical axis direction.
 5. The voice coil motor of claim1, wherein the elastic member comprises a lower elastic member disposedon a lower surface of the bobbin, wherein the lower elastic membercomprises two lower elastic members, and wherein each of the two lowerelastic members comprises an inner elastic unit coupled to the bobbin,an outer elastic unit coupled to the base unit and a connection elasticunit connecting the inner elastic unit and the outer elastic unit. 6.The voice coil motor of claim 3, wherein the recess portion is formed oneach of both lateral surfaces of each of the plurality of rotationprevention units of the bobbin.
 7. The voice coil motor of claim 1,wherein an object collecting member is disposed on a floor surface of agroove formed by the rotation prevention unit.
 8. The voice coil motorof claim 7, wherein the object collecting member comprises an epoxyresin having a viscosity.
 9. The voice coil motor of claim 1, furthercomprising a cover wrapping the bobbin and coupled to the base unit. 10.The voice coil motor of claim 1, wherein the lateral surface of theinner unit of the yoke comprises a first portion corresponding to therecess portion and a second portion facing the lateral surface of therotation prevention unit, and wherein when the bobbin is rotated, thesecond portion of the lateral surface of the inner unit of the yoke isconfigured to contact the lateral surface of the rotation preventionunit and the first portion of the lateral surface of the inner unit ofthe yoke does not contact the rotation prevention unit.
 11. The voicecoil motor of claim 10, wherein the second portion of the lateralsurface of the inner unit of the yoke is disposed below the firstportion of the lateral surface of the inner unit of the yoke, andwherein the second portion of the lateral surface of the inner unit ofthe yoke is disposed on the same plane as the first portion of thelateral surface of the inner unit of the yoke.
 12. The voice coil motorof claim 10, wherein a length of the lateral surface of the rotationprevention unit is greater than a length of the first portion of theinner unit of the yoke in direction of an optical axis.
 13. The voicecoil motor of claim 1, wherein the inner unit of the yoke comprises anobject occurrence preventing portion formed on the lateral surface ofthe inner unit of the yoke opposite to the lateral surface of therotation prevention unit, and wherein the object occurrence preventingportion of the inner unit of the yoke is formed by cutting a portion ofthe inner unit of the yoke.
 14. A camera module, comprising the voicecoil motor of claim 1; a lens coupled to the bobbin of the voice coilmotor; and an image sensor.
 15. A mobile phone comprising the cameramodule of claim
 14. 16. A voice coil motor, comprising: a base unit; abobbin comprising a rotation prevention unit formed on an outerperipheral surface of the bobbin; a coil disposed on the outerperipheral surface of the bobbin; a yoke comprising an upper plate, alateral plate extending from the upper plate and an inner unit extendingfrom the upper plate, a magnet disposed between the coil and the lateralplate of the yoke and facing the coil; and an upper elastic membercoupled to an upper surface of the bobbin, wherein at least a portion ofthe inner unit of the yoke is disposed between the bobbin and the coilto be hitched by the rotation prevention unit to prevent rotation of thebobbin, wherein a recess portion recessed from the upper surface of thebobbin to decrease a contact area between the rotation prevention unitof the bobbin and the inner unit of the yoke.
 17. The voice coil motorof claim 1, wherein the rotation prevention unit of the bobbin comprisesa lateral surface comprising a first area and a second area recessedfrom the first area, wherein the inner unit of the yoke comprises alateral surface comprising a third area corresponding to the first areaof the rotation prevention unit in a horizontal direction and a fourtharea corresponding to the second area of the rotation prevention unit inthe horizontal direction, and wherein a distance between the second areaof the rotation prevention unit and the fourth area of the inner unit ofthe yoke is greater than a distance between the first area of therotation prevention unit and the third area of the inner unit of theyoke.
 18. The voice coil motor of claim 17, wherein the fourth area ofthe inner unit of the yoke does not contact the rotation prevention unitof the bobbin, when the third area of the inner unit of the yokecontacts the rotation prevention unit of the bobbin by rotation of thebobbin.
 19. The voice coil motor of claim 1, wherein a length of thefirst area of the rotation prevention unit is greater than a length ofthe second area of the rotation prevention unit in a direction of anoptical axis.
 20. A voice coil motor, comprising: a base unit; a bobbinhaving a rotation prevention unit; a coil disposed on the bobbin; a yokecomprising an upper plate, a lateral plate extending from the upperplate and an inner unit extending from the upper plate and disposed inthe lateral plate, a magnet disposed between the coil and the lateralplate of the yoke and facing the coil; and an elastic member coupled tothe bobbin, wherein the inner unit of the yoke is configured to behitched by the rotation prevention unit to prevent rotation of thebobbin.